1. Field of the Invention
This invention relates to a substrate processing apparatus and a method for manufacturing a semiconductor device.
2. Description of the Related Art
Conventionally, in a semiconductor manufacturing process, a CVD apparatus, an oxide film forming apparatus, a diffusion apparatus or the like is used to perform film formation of an oxide film or a thin film of Si3N4 film and the like on a surface of a semiconductor substrate, which is a body to be processed, for example, a semiconductor wafer, or to perform diffusion of impurities. Recently, a substrate processing apparatus using a vertical type thermal treatment furnace is utilized in order to perform processing with high accuracy.
In a vertical type reaction furnace which is such a substrate processing apparatus, generally as shown in FIG. 3, a tube-shaped furnace having a heater 1 for heating is vertically disposed, and within this tube-shaped furnace, an inner reaction tube 3 and an outer reaction tube 2 made of quartz are provided. A furnace opening flange 4 which is an inlet adapter is provided at a lower end of the outer reaction tube 2 via an O-ring, and a lower end of the inner reaction tube 3 is secured to an inner circumferential surface of the furnace opening flange 4. Moreover, a process gas introduction tube (a process gas introduction nozzle) 18 which is a process gas supply line is allowed to be in communication with a furnace opening 27 configured as an inside space of the furnace opening flange 4.
On the other hand, many semiconductor wafers 16 which are substrates to be processed are accommodated and loaded in a boat 15 in a vertical direction with the respective wafers being in a horizontal state. The boat 15 is then placed on a boat support base 13, and loaded into the above-said inner reaction tube 3 by allowing the boat 15 to move up by an appropriate hoisting and lowering apparatus. A furnace opening 27 is then airtightly covered with a furnace opening seal which comprises a disk-shaped cover body 7 at a lower part of the boat support base 13 via an O-ring 5 so that one closed substrate processing space (a reaction chamber) 26 is formed. Moreover, the boat support base 13 is supported by a rotation shaft 11 so that it is constructed to be rotatable by a boat rotation mechanism 10.
An appropriate reaction gas (process gas) is introduced into the inner reaction tube 3 which constructs such a reaction chamber, from the process gas introduction tube (process gas Introduction nozzle) 18 which is a process gas supply line. The reaction furnace is constructed to perform prescribed processing, for example, of performing film formation of a thin film of SiN4 film on silicon wafers, and the like, in the furnace using the reaction gas. In addition, 25 represents a gas exhaust tube.
In such wafer processing, the boat 15 and the boat support base 13 are allowed to rotate by the boat rotation mechanism 10 in order to improve uniformity of a CVD film generated on the wafers.
As mentioned above, the wafers 16 are loaded onto the boat 15 and heated by a heater 1, at the same time, the process gas is introduced from the process gas introduction tube (the process gas in) 18, and the gas passes through the wafer region to allow a gas phase chemical reaction to be performed, and an exhaust gas is exhausted from a gas exhaust tube (a process gas out) 12 whereby the wafer processing is performed.
Here, in the wafer processing wherein the boat 15 and the boat support base 13 are rotated by the boat rotation mechanism 10 in order to improve uniformity of a CVD film formed on the wafers, a conventional problem is that, when the boat rotation mechanism 10 is installed to be exposed to an inside of the reaction chamber, by-products in the wafer processing adhere to its rotation mechanism portion so that the rotation mechanism 10 is allowed to seize.
As a solution to such a disadvantage, an application of known techniques such as the following (a), (b) and (c) which prevent the process gas from entering a circumference of a rotation shaft of the rotation mechanism, is considered to be effective.
For example, (a) Japanese Patent Application Laid-Open No 2000-286204 and (b) Japanese Patent Application Laid-Open No. 6-302533 disclose a technique wherein, in order to prevent corrosion by the reaction gas of metal parts such as a boat rotation shaft and the like, a portion with concavities and convexities which interpose one another is formed at a lower surface of a boat cap made of quartz (a boat support base) and at an upper surface of a base made of quartz (a cover body), and N2 gas is injected into a gas flow passage formed by a clearance between the concavities and convexities from a side of the rotation shaft.
Moreover, (c) Japanese Patent No. 2,691,159 discloses a technique wherein, in a construction which covers a furnace opening with a cover body 59 made of metal (stainless), as shown in FIG. 4, a barrier 63 made of quartz is provided around a circumference of a magnetic fluid seal unit 62 of a rotation shaft 61, and a purge gas is introduced into a purge gas supply space 73 formed by the barrier 63 made of quartz and a lower surface of a turntable 64 so as to allow a pressure of the space to be at a positive pressure compared to a pressure in a reaction vessel thereby preventing intrusion of a reaction gas into the magnetic fluid seal unit 62.
However, the conventional techniques (a) and (b) use the cover body made of quartz and the boat cap made of quartz for forming the gas flow passage around the circumference of the boat rotation shaft and providing the flow passage resistance (conductance) thereby resulting in a very high cost. Additionally, due to complexity of constructions such as lines and the like in a furnace opening portion of a CVD furnace, the constructions are difficult to manufacture from quartz and are liable to have insufficient strength to be able to stand.
Moreover, the conventional technique (c) has the construction wherein the barrier 63 of quartz is provided at a side of the cover body (made of metal), and the purge gas supply space 73 is formed by the barrier 63 and a rotation wall opposite to the barrier, and a purge gas is fed from the space to a side of the rotation shaft which has a narrow space, so that the purge gas has difficulty in passing through in a direction of the rotation shaft whereby a perfect purge can not be easily performed. In addition, because the barrier having a special configuration which is relatively large is constructed from quartz, the construction is also difficult to manufacture, liable to have insufficient strength to be able to stand, and at a high cost, as is the case with the conventional techniques (a) and (b). Further, in the case of the conventional technique (c), the cover body 59 is exposed to the inside of the furnace so that the cover body 59 tends to become a source of pollution of a reaction atmosphere.
Furthermore, although the cover body is preferably provided with a cooling passage therein for cooling an O-ring, as shown in the conventional technique (b), the entire cover can be cooled due to high thermal conductivity of metal. As a result, by-products adhere to the cover body so that the cover body is liable to become a source of pollution of a reaction atmosphere.
Therefore, an object of the present invention is to provide a substrate processing apparatus and a method for manufacturing semiconductor device wherewith, by resolving the problems of the prior art that semiconductor film by-products are incorporated into a boat rotation mechanism so as to allow the mechanism portion to be locked, a high quality semiconductor film can be generated with stability for a long period of time.
In order to attain the above-described object, the present invention is constructed as follows:
The invention of claim 1 resides in a substrate processing apparatus comprising: a reaction chamber with an opening which defines a processing space; a heater which heats a substrate; a substrate supporting member which supports the substrate in said reaction chamber; a cover body, made of metal, which covers the opening of said reaction chamber via a seal member; a rotation mechanism which rotates said substrate supporting member supported by a rotation shaft; a flow passage, provided in said cover body, which cools said seal member; and an extending member which extends from said substrate supporting member; wherein the extending member includes: a drooping portion which extends in a direction from the substrate supporting member toward the cover body; and an extending portion which extends radially outwardly from a lower end of the drooping portion toward a reaction chamber wall and extends along a surface of the cover body exposed to the processing space.
According to the present invention, the cover body is made of metal so that the cover body is easy to manufacture compared to the case wherein the cover body is made of quartz, so as to allow the present invention to be advantageous with respect to cost. Additionally, the extending member which is provided from the substrate supporting member to the cover body is not only constructed to include the drooping portion which extends downwardly from an outer circumferential portion of the lower end of the substrate supporting member, but also constructed to include the extending portion which extends radially outwardly from the drooping portion, wherein the extending portion extends along the processing space exposed surface of the cover body toward the reaction chamber wall. This effectively provides a resistance (conductance) of a flow passage around a circumference of a rotation shaft in a radial section wherein the extending portion and the processing space exposed surface of the cover body are superimposed each other. A shielding construction of a rotating body constructed in such a manner as to allow a reactive gas to have difficulty in coming around to a rotation mechanism for rotating a substrate supporting member thereby being able to avert a situation where a rotation portion does not work. In addition, in the present invention, it is necessary only to provide the extending member, and it is not necessary to form and provide the barrier 63 made of quartz which is large and has the special configuration as in the conventional technique (c) explained in FIG. 4.
Further, in the present invention, since the extending portion of the extending member and the processing space exposed surface of the cover body are superimposed each other in the radial section, giving and receiving of heat between both the members is effectively conducted. That is, although the cooling flow passage for seal member which is formed inside of the cover body made of metal attempts to cool the cover body, the cover body effectively receives heat from the extending portion of the extending member so as to be warmed. This avoids a disadvantage wherein a temperature of the cover body is reduced so that by-products in substrate processing are liable to adhere to the cover body.
The invention of claim 2 resides in a substrate processing apparatus according to claim 1, wherein a clearance between said surface of the cover body and the extending portion of said extending member and a clearance between said reaction chamber wall and the extending portion of said extending member are formed to be relatively narrow r, 1 to 5 mm respectively.
The reason why lower limits of the clearance between the above-described surface of the cover body and the extending portion of the extending member and the clearance between the above-described reaction chamber wall and the extending portion of the extending member are set to be 1 mm or more is that less than 1 mm makes it difficult to realize assembling due to mechanical dimensional accuracy so that 1 mm becomes a limit. Additionally, the reason why upper limits of the clearances are set to be 5 mm or less is that the clearances having a size of more than 5 mm makes it difficult to provide an effective flow passage resistance (conductance) between the rotation mechanism and a reaction chamber and also allows a warming action by the extending member of the cover body to become ineffective.
The invention of claim 3 resides in a substrate processing apparatus comprising: a reaction chamber with an opening which defines a processing space: a heater which heats a substrate; a substrate supporting member which supports the substrate in said reaction chamber; a cover body, made of metal, which covers the opening of said reaction chamber via a seal member; a flow passage, provided ind said cover body, which cools said seal member; and an extending member which extends from said substrate supporting member and extends along a proximity of a surface of the cover body exposed to the processing space; wherein said cover body is warmed with heat which transfers from said substrate supporting member to said extending member.
In the present invention of claim 3, heat transferred from the substrate supporting member to the extending member warms the cover body. In the case that giving and receiving of heat between both the members is not performed effectively, the cooling flow passage which is formed inside of the cover body made of metal cools the cover body so that by-products in substrate processing is liable to adhere to the cover body. However, in the present invention, since the cover body is effectively warmed with the heat from the extending member so as to avoid a disadvantage wherein a temperature of the cover body is reduced so that by-products in substrate processing is liable to adhere to the cover body.
The invention of claim 4 resides in a substrate processing apparatus according to claim 3, wherein a clearance between said extending member and said surface of the cover body is formed to be of the order of 1 to 5 mm.
The reason why a lower limit of the clearance between the extending member and the surface of the above-stated cover body is set to be 1 mm or more is that less than 1 mm makes it difficult to realize assembling due to mechanical dimensional accuracy so that 1 mm becomes a limit. Additionally, the reason why an upper limit of the clearance is set to be 5 mm or less is that the clearance having a size of more than 5 mm allows a warming action by the extending member of the cover body to become ineffective.
The invention of claim 5 resides in a method for manufacturing a semiconductor device, comprising:
supporting a substrate on a substrate supporting member; inserting said substrate supporting member into a reaction chamber; covering an opening of the reaction chamber with a cover body made of metal via a seal member; rotating said substrate supporting member by a rotation shaft of a rotation mechanism; flowing a purge gas radially outwardly from a side of the rotation shaft along a flow passage formed between the surface of said cover body exposed to a processing space and an extending member which extends from said substrate supporting member and extends radially outwardly along the surface of the cover body exposed to the processing space; introducing a reaction gas into the reaction chamber in order to process said substrate; and exhausting said introduced reaction gas from an inside of said reaction chamber.
According to the invention described in claim 5, after the step is performed which flowing a purge gas along a flow passage formed between the surface of said cover body exposed to a processing space and an extending member which extends from said substrate supporting member and extends radially outwardly along the surface of the cover body exposed to the processing space, the step is performed which introduces the reaction gas into the reaction chamber in order to process the said substrate. The purge gas is flowed radially outwardly from the side of the rotation shaft and a perfect purge is conducted around a circumference of the rotation shaft of the substrate supporting member so that air and the like do not remain around the circumference of the rotation shaft.
The invention of claim 6 resides in a method for manufacturing a semiconductor device, comprising:
supporting a substrate on a substrate supporting member; inserting said substrate supporting member on which said substrate is supported, into a reaction chamber from an opening of said reaction chamber in which a processing space is formed; covering the opening of the reaction chamber with a cover body made of metal via a seal member; flowing a fluid into a flow passage provided in said cover body for cooling said seal member; heating said substrate; including an extending member which is extended from said substrate supporting member and extends along a proximity of a surface of the cover body exposed to said processing space and warming said cover body with heat which transfers from said substrate supporting member to said extending member; introducing a reaction gas into said reaction chamber in order to process said substrate; and exhausting said introduced reaction gas from an inside of said reaction chamber.
According to the invention described in claim 6, although the cover body is cooled in flowing a fluid into a flow passage for cooling the seal member, added is warming the cover body with heat which transfers from the substrate supporting member to the extending member. Therefore, by-products in substrate processing is not liable to adhere to the cover body.
The invention of claim 7 resides in a method for manufacturing a semiconductor device according to claim 5 or 6, wherein a clearance between said extending member and said surface of the cover body is formed to be of the order of 1 to 5 mm.
According to the invention described in claim 7, when a clearance between the extending member and the surface of the cover body is formed to be of the order of 1 to 5 mm, a warming action by the extending member of the cover body becomes more effective.